A projection type video display is so configured that light emitted from a light source is modulated by a light valve such as a liquid crystal panel to be projected, so that it must comprise a high-luminance light source. Consequently, measures to prevent heat generated from the high-luminance light source itself and heat generated when light is absorbed in a light polarizing plate in the liquid crystal panel or various types of optical components are required. Conventionally, a projection type video display has a structure in which air is sucked and exhausted and heat is released from the device by rotating a fan with a motor (see JP-A-2001-222065)
In a suction and exhaust mechanism using motor driving, however, noises are produced due to suction and exhaust sound by rotating sound of a motor and hissing sound of a fan. As a result, there is a disadvantage that the noise produced by the suction and exhaust sound is offensive to the ear when a projector is used.